KHAR, Pakistan — Al Qaeda's second in command, Ayman al-Zawahiri, had visited a madrasa destroyed by a Pakistani Army helicopter attack, but he was not there when the missiles struck on Monday, senior Pakistani security officials said.

Several other Qaeda leaders had passed through the religious school run by a pro-Taliban cleric, Maulana Liaqatullah, who was killed in the airstrike along with about 80 of his followers, the officials said Tuesday.

Among the other militants known to have frequented the madrasa at Chenagai, a village near the Afghan border in the Bajaur tribal region of northwest Pakistan, was Abu Ubaida al-Misri.

An Egyptian, Misri was identified as the mastermind of a plot, foiled earlier this year, to blow up U.S.-bound airliners flying from Heathrow Airport.

No major militant figure was believed to have been present when the army attacked, and orders for the assault were given in anticipation that the militants were about to be sent to fight - possibly to launch suicide attacks on NATO and Afghan forces.

"The madrasa was under surveillance since July when the activity started picking up pace," a senior official said.

In January, the CIA targeted Zawahiri in a Predator missile attack in the village of Damadola in Bajaur.

Intelligence officials said a handful of Qaeda operatives at a conference hosted by Liaqatullah had been killed in the January attack. But Zawahiri did not attend and reports that Misri had been killed proved incorrect.

The Pakistani government had been trying to persuade militant tribesmen in Bajaur to agree to peace terms along the lines of accords brokered earlier in the two most restive tribal regions, North and South Waziristan.

But officials said Liaqatullah and another militant, Maulana Faqir Mohammed, who rallied fighters at the site of the destroyed madrasa immediately after the attack, had ignored those efforts.

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The officials showed reporters aerial footage, taken through a night-vision lens, of rows of men exercising before daybreak, an hour before the missiles struck the compound.

Tribesmen said the dead, mostly young men aged 15 to 25, had been students, not militants. The Pakistani president, General Pervez Musharraf, speaking at a seminar in Islamabad, said they had all been militants.

"We know who they were," Musharraf said. "They were doing military training."

In Khar, the main town in Bajaur, more than 15,000 armed tribesmen protested against the attack and Islamist politicians stoked anti-Western and anti-Musharraf sentiment among ethnic Pashtuns in several towns throughout North West Frontier Province.

Nowhere is Musharraf's alliance with the United States more unpopular than in the Pashtun tribal belt straddling the Pakistan-Afghan border.

The tribesmen in Khar showed their loyalty with shouts of "Long Live Osama" and "Long Live Mullah Omar."

Islamist politicians said the attack on the school had been carried out by a Predator drone aircraft, but Pakistan's military spokesman and a U.S. spokesman in Kabul denied the claim.

Bomb kills 2 NATO soldiers

A roadside bomb killed two NATO soldiers and wounded two others on patrol in eastern Afghanistan on Tuesday, The Associated Press reported the alliance as having said in Kabul.

The roadside bomb struck the soldiers' vehicle in the province of Nuristan, NATO said. The two wounded soldiers were taken to a U.S. military facility in Asadabad in Kunar Province.

NATO did not disclose the nationalities of the soldiers.

Afghanistan has seen a sharp rise in violence over the last several months, particularly in the southern and eastern provinces near the border with Pakistan. Militants have been increasingly using roadside and suicide bombs in their attacks against Western and Afghan security forces.